Lobular carcinoma in situ. Pathology and treatment.

Lobular carcinoma in situ is a relatively "new" breast lesion, having been described only 50 years ago. It was originally thought to be a stage in the progression to invasive lobular cancer, but current evidence suggests that it is a marker of increased risk. It is certainly the most powerful of all risk factors, with studies suggesting that approximately 20 to 30 per cent of patients will go on to develop invasive cancer of various histologic types and with equal frequency in the biopsied and the opposite breast. There is general agreement concerning these facts, but considerable controversy remains about treatment. Haagensen and coworkers pioneered the concept of observation at a time when unilateral mastectomy was the standard treatment. Observation has gradually been accepted by the majority of American physicians, but it is a slim majority, and the patient's wishes will properly continue to play a role in the final decision.